None of his physical assessments since then have shown any sign of awareness, or ability to communicate.

But the British neuroscientist Prof Adrian Owen - who led the team at the Brain and Mind Institute, University of Western Ontario - said Mr Routley was clearly not vegetative.

"Scott has been able to show he has a conscious, thinking mind. We have scanned him several times and his pattern of brain activity shows he is clearly choosing to answer our questions. We believe he knows who and where he is."

Prof Owen said it was a groundbreaking moment.

Finding a voice for the brain injured"Asking a patient something important to them has been our aim for many years. In future we could ask what we could do to improve their quality of life. It could be simple things like the entertainment we provide or the times of day they are washed and fed."

Scott Routley's parents say they always thought he was conscious and could communicate by lifting a thumb or moving his eyes. But this has never been accepted by medical staff.

Prof Bryan Young at University Hospital, London - Mr Routley's neurologist for a decade - said the scan results overturned all the behavioural assessments that had been made over the years.

Functional Magnetic Resonance Imaging measures the real-time activity of the brain by tracking the flow of oxygen-rich bloodThe patients were repeatedly asked to imagine playing tennis or walking around their homeIn healthy volunteers each produces a distinct pattern of activity, in the premotor cortex for the first task and the parahippocampal gyrus for the secondIt allowed the researchers to put a series of yes or no questions to severely brain-injured patients. A minority were able to answer by using the power of thoughtIn 2010 Prof Owen published research showing that nearly one in five of the vegetative patients were able to communicate using brain activity"I was impressed and amazed that he was able to show these cognitive responses. He had the clinical picture of a typical vegetative patient and showed no spontaneous movements that looked meaningful."

Observational assessments of Mr Routley since he responded in the scanner have continued to suggest he is vegetative. Prof Young said medical textbooks would need to be updated to include Prof Owen's techniques.

The BBC's Panorama programme followed several vegetative and minimally-conscious patients in Britain and Canada for more than a year.

Another Canadian patient, Steven Graham, was able to demonstrate that he had laid down new memories since his brain injury. Mr Graham answers yes when asked whether his sister has a daughter. His niece was born after his car accident five years ago.

The Panorama team also followed three patients at the Royal Hospital for Neuro-disability (RHN) in Putney, which specialises in the rehabilitation of brain-injured patients.

It collaborates with a team of Cambridge University neuroscientists at the Wolfson Brain Imaging Centre at Addenbrooke's hospital, Cambridge.

Panorama's Fergus Walsh meets Professor Adrian Owen to learn what the brain is like when in a vegetative stateOne of the patients is diagnosed as vegetative by the RHN, and he is also unable to show awareness in an fMRI machine.

A second patient, who was not able to be fully assessed by the RHN because of repeated sickness, is later shown to have some limited awareness in brain scans.

Makes you think though. If you have a relative who is in a coma, do they know some of their loved ones aren't visiting because they think they're brain dead?

What if they do know? What if they sit there thinking to themselves, "I wish they would stop by once in awhile." It could allow us to "talk" to them when we previously may have thought it was impossible.

That is pretty mind blowing all around and one heck of a discovery. Really interested in what else they find out and how this can improve patient care. Can't imagine what families going through this sort of ordeal are experiencing but this has got to provide some comfort being able to communicate (even on very basic levels) with loved ones.